In general, blixing solution concentrate compositions for use with silver halide color photographic materials are desired to facilitate handling, to be convenient, to reduce transportation costs and to reduce packaging costs, and the processing solutions are provided as concentrates which are diluted with water for use when required.
These blixing solution concentrate compositions are divided into a number of parts, thus separating the components to enable concentration to be achieved while maintaining stability.
Conventionally, blixing solution concentrate compositions for color printing purposes have been provided in two parts, which is to say, a part (Part (A)) of pH 6 to 8 containing a reducing compound comprising a silver halide solvent and a preservative as the main components, and a part (Part (B)) of pH 4 to 6 containing an oxidizing compound of which a bleaching agent is the main component. In practice, the designated quantities of the two parts are mixed together for use and the pH is adjusted, as required, and the pH of the solution which is used is generally in the range from 6 to 7. However, more recently, use has been made of solutions which have a lower pH of from 4 to 6 in use in order to shorten the desilvering time to speed up processing. Consequently, it has been necessary to provide a further part (Part (C)) which contains an acid for adjusting the pH as the main component. Hence, the concentrate has been provided in three parts, but this has proved to be inconvenient in respect of ease of handling, convenience, transportation costs and low packaging material costs.
Part (C) must be packed separately because the sulfite which is normally used as a preservative becomes unstable and decomposes if the pH of Part (A) is reduced, while if the pH of Part (B) is reduced then the EDTA Fe(III), the bleaching agent normally used, may be reduced to form an Fe(II) with a loss of oxidizing ability. The EDTA chelating agent may precipitate out, and it becomes difficult to provide a uniform composition. Hence, Part (C) in which the acid for pH adjustment is isolated, must be provided separately and in practice the composition must be provided in three parts.